slightly OT, JX-8p

Fraser, Colin J Colin.Fraser at scottishpower.plc.uk
Mon Nov 15 13:29:41 CET 1999


> -----Original Message-----
> From: WeAreAs1 at aol.com [mailto:WeAreAs1 at aol.com]
> Sent: 13 November 1999 21:28
> To: PlanetZ at mediaone.net; synth-diy at mailhost.bpa.nl; helin at uta.fi
> Subject: Re: Re: slightly OT, JX-8p
> 
> Most of the later model Rolands that had companion programmer 
> units (the 
> MKS80, D50, MKS50, D20, etc.) actually used their regular 
> MIDI Input jack as 
> the programmer input (with an additional merging MIDI Input 
> jack on the 
> programmers, for connecting your keyboard controller).  Those 
> programmer 
> units were simply sending MIDI sysex data, unlike the 
> proprietary data 
> formats used in the PG200 and PG800.

I've been reverse engineering the JX10 firmware since I picked one up
recently without the programmer.
I had hoped to use sysex to edit the sounds, but the JX10 doesn't support
this.

The JX8P and JX10 both have a separate assigner CPU, and voice board CPU (2
for the JX10).

The communication between the assigner CPU and the voice boards is send via
the UART out of the assigner, and received at the UART input of the voice
board cpu.
This is basically a midi connection with the use of some non-standard midi
commands.
These extra commands allow the assigner board to control the voice board
tone parameters and voice allocation.
The JX's midi out is driven by one of the voice board cpus. One of the extra
commands instructs it to pass all received data.
This saves the assigner from needing a second UART.

The PG800 connects via a synchronous serial interface to the assigner CPU
and generates control messages in the same format as the voice board
commands - they are basically just passed on to the voice board, with a
header message to tell it to expect them.

I have worked out the command set used, and will be starting work on a clone
of the PG800 as soon as the plasterers and decorators are finished replacing
the ceiling in my workshop.
I'll put some details on my web page when time allows.

There are 700 bytes of space left in the version 2.0 firmware for the JX10,
so if that is enough, I will be adding sysex editing of parameters too. In
fact the JX8P/MKS70 sysex editing format encapsulates the proprietary
command format, with only a missing MSB in the command bit, so the
conversion is not too involved.
If it's not enough space, the sequencer wil have to go...

Any JX10 owners on the list can mail me privately if they would be
interested in this upgrade.


Colin f



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